Plural-barrel gun with drum and chambering mechanism



J. F. OBRIEN Nov; 8, "1960' PLURAL-BARREL GUN WITH DRUM AND CHAMBERING MECHANISM Filed April 7. 195s 2 Sheets-Sheet 1 4 4 @Qwi/ INVEiJTOR. Ju'hn F. O'Brien w a 44W Nov. 8, 1960 J. F. O'BRIEN PLURAL-BARREL GUN WITH DRUM AND CHAMBERING macwmxsu Filed April 7, 1958 2 Sheets-Sheet 2 INVENTOR.

PLURAL-BARREL GUN WITH DRUM AND CHAMBERING MECHANISM John F. OBrien, Springfield, Mass., assignor to the United States of America as represented by the Secretary of- (Granted under Tifle 35, US. Code (1952), see. 266) The invention described hereinmay be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to machine guns having multiple barrels which are rotated responsive to the discharge .of cartridges'thereinto and more particularly to a chamber mechanism for such guns. This application is a continuation-in-part of the application by John F. OBrien for Rotoramic Machine Gun, Serial No. 560,909, filed January 23, 1956, and now abandoned.

One of the objects of this invention is to provide a machine gun in which the moving parts are all actuated transversely to the longitudinal axis of the gun so as not to be affected by longitudinal accelerative forces when mounted to a vehicle, such as an aircraft.

Another object of this invention is to provide for a machine gun having multiple barrels disposed for rotation responsive to thefiring thereof, separate and disconnected chamber members for the barrels to reduce the mass of the actuating parts of the gun and thereby increase the firing rate thereof.

It is a further object of this invention to provide for such a machine gun separate chamber memberswhich are self-supportingly mounted inside the gun receiver for continuous travel therearound.

It is still another object of .this invention to provide for such a gun separate chamber members which are selfsupportingly mounted in the gun receiver for rotary travel therearound in a transverse section so as to pass through the firing station of the gun simultaneously with one of the barrels and to proceed radially apart from the barrels to enable unidirectional feeding of cartridges into the chamber members and extraction of the fired cases therefrom.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. 1 is a partially cross-sectioned side view of the firearm;

Fig. 2 is a view taken alongline 22 of Fig. 1;

Fig. 3 is a view taken along line 3--3 of Fig. 1;

Fig. 4 is a view taken along line 4-4 of Fig. 1; and

Fig; 5 is a view taken along line 5-5 of Fig. 1.

Shown in the figures is a machine gun 12 for automatically firing cartridges 14 each of which includes a projectile 15 inclosed within'a cylindrical case 16.- Such gun is provided with a substantially cylindrical receiver 18 which houses a cylindrical drum 20 mounted by spline means on a longitudinally disposed shaft 22 rotatably mounted in the receiver. Five barrels 24 are mounted through drum 20 so that the rear ends are substantially flush with the rear face of the drum and so as to be symmetrically disposed therein respective to shaft 22 and to each other. Drum 20 is rotataed by the operation of gun 12, through means hereinafter explained, so that the barrels 24 pass successively through a firing station which is disposed in the area of intersection of the path of the barrels, when closest to the bottomof receiver 18, with the vertical plane of gun 12.

The cartridges 14 are chambered for discharge into the barrels 24 in a plurality of separate chamber members 26 which are'successively alignable, as hereinafter explained, with successive ones of the barrels 24 when in the firing station and each of the chamber members is provided with an axial firing chamber 28 which permits the passageof the cases 16 therethrough. There are eight of the chamber members 26 in the present embodiment and they are disposed in an endless train for travel around a raceway 36 provided on the inside of receiver 18 in a transverse section. Raceway 30 is substantially elliptical in shape, as best shown in Fig. 3, and is disposed adjacent the rear face of drum 20. Referring particularly to Fig. 3, raceway 30 is seen to include laterally opposed rounded ends 32 from which a pair of tangential portions 34 extend downwardly to converge at the vertical plane of gun 12 so as to form an arcuate cradle 35 for one of the chamber members 26 when at the firing" station so as to support such chamber member in axial alignment with one of the barrels 24 when also positioned at the firing station. The upper portions of the ends 32 are joined by an arcuate portion 36 which is concentric to shaft 22 and which defines the charging station for the chamber members 26 by being so disposed that when the chamber members travel around such arcuate portion the firing chambers of such chamber members are clear of the outside perimeter of drum 20 so that the cases 16 in such firing chambers may be pushed forwardly from the chambers as hereinafter described. The expelled cases 16 are received by mating troughs 37 provided in the outside periphery of drum 20 so as to be delivered thereby to a. port 39 in receiver 18 for ejection from gun 12.

Arcuate portion 36 and the end 32 form a channel 38, the front and rear walls of which restrain the chamber members from longitudinal displacement. During travel along the tangential portions 34, the chamber members 26 are confined between the rear face of drum 20 and the front face of a back plate 40 provided on a sprocket wheel 42 which is fixedly mounted by spline means to shaft 22 immediately rearward of drum 20.

The train of chamber members 26 is self-supported in raceway 30 for travel therearound as the circumferential dimension and shape of such raceway is such that the minimum distance between the outside peripheries of alternate ones of the chamber members 26 is smaller than the diameter of the chamber member therebetween, whereby, the weight of the chamber members disposed along arcuate portion 36 presses, as best shown in Fig. 3, the lower chamber members against the tangential portions 34 to carnmingly force the central chamber member into cradle 35 formed thereby and such chamber members in the charging station are flexibly supported in turn to conform to the arc of arcuate portion 36 so that the axes of such chamber membres move in an are concentric with such arcuate portion. The train of chamber members 26 is rotated around raceway 30 by the sprocket Wheel 42 which is provided with a plurality of tooth portions 44 equal to the number of barrels 24 and such tooth portions are disposed to form tooth spaces 45 each of which is longitudinally aligned with one of the barrels. The tooth portions 44 are also disposed to securely grip one of the chamber members therebetween when such chamber member is in the firing station and to engage successive ones of such chamber members for successively moving the chamber members through the firing station in synchronism with the barrels 24 and rotating such train. The back plate 40 is disposed to close the rear ends of the chambers of the chamber members 26 when in the firing station, and provided in such plate are five electrical firing pins 46 which are respectively engageable with the primers of the cartridges 14 when engaged between the tooth portions 44 in the firing station.

A feedwheel 48 is also mounted to shaft 22 for rotation therewith by spline means and is connected by gear means (not shown) to a feed sprocket 50 which is disposed to sequentially deliver cartridges 14 from a conduit 52, leading to a supply hopper (not shown), to feedwheel 48 during rotation of such shaft by operation of gun 12. Feedwheel 48 is provided with nine substantially semi-circular carriers 54 which are fixedly mounted in mating recesses in the perimeter of such feedwheel so that the trailing edges of such carriers, respective to the rotation of such feedwheel, project outwardly from the perimeter of the feedwheel, as noted at 55 in Fig. 2, to engageably transfer cartridges 14 from feed sprocket Stl to corresponding ones of the carriers.

The carriers 54 are so disposed in feedwheel 48 that the distance from the axes of the carriers to the axis of shaft 22 is the same as the distance from the axis of the shaft to the axes of the chamber members 26 when moving through the charging station so that the cartridges 14 carried by such carriers may be readily transferred therefrom to the chamber members in the charging station. Such transfer is effected by a forwardly facing spiral cam 68 which is disposed in the upper half of receiver 18 rearwardly of arcuate portion 36 so as to be engage.- able by the bases of the cartridges 14 being carried in feed-wheel 48 through the charging station. Whereby, the cartridges 14 are progressively moved into the cham ber members 26, while traveling through the charging station, to push forwardly therefrom the fired cases 16.

Extending radially into drum 29 intermediate the barrels 24 are five bottomed bores 58 from the inner ends of which holes as extend to the bore of each of the barrels whereby each of the bores 53 is in communication with one of the barrels. A piston 62 is slidably mounted in each of the bores 58 and mounted to such piston is a rotary follower 64. Provided in receiver 18, as best shown in Fig. 5, is a cam portion 65 which is disposed for engagement by the follower 64 on the piston 62 which is mounted in the bore 58 having communication with the one of the barrels 24 which is in the firing position, whereby, the gases from the discharge of a cartridge 14 into such barrel provides rotation of such drum.

Thus, when gun 12 is triggered for operation, by means (not shown), the discharges of the cartridges 14 at the firing station produce continuous rotation of drum 2t and, therefore, of shaft 22 and sprocket wheel 42 and feedwheel 48 mounted thereon. Through the rotation of sprocket wheel 42 the fired cases 16 are moved around to the charging station and live cartridges 14 are moved through the firing station by the engagement of the tooth portions 44 with the chamber members 26 carrying such cartridges and cases. As the chamber members 26 carrying the fired cases in are moved to the charging station, the bases of the live cartridges M which are aligned therewith in the carriers 54, engage spiral cam 68 and are progressively pushed forwardly thereby into the aligned ones of the firing chambers 26. The forward movement of the cartridges 14 into the firing chambers 26 pushes forwardly therefrom the fired cases 16 which are received by one of the troughs 37 in the periphery of drum 20 to be carried thereby to port 39 for ejection from gun 12.

From the foregoing it is clearly apparent that there is herein provided for machine guns having multiple barrels mounted for rotation therein an improved chambering mechanism whereby the mass of the moving parts is reduced by providing for the barrels a plurality of separate chamber members which are se'lf-supportiugly mounted in the gun receiver. The chamber members are also arranged for travel around the inside of the receiver so that the firing chambers 26 are clear of the barrel supporting drum when moving through the charging station so that the cartridges moved by cam 63 into the chamber members may simultaneously push the fired cases forwardly therefrom to eliminate the loss of time required to extract the fired cases rearwardly from the chambers before the feeding of live cartridges thereinto, as with conventional guns, and the need for intricate extracting mechanisms. There is seen that through such chambering mechanism the moving parts are all moved transversely to the longitudinal axis of the gun so that any longitudinal accelerative forces, produced as when mounted to an airplane, will not affect the operation of the gun to cause malfunction thereof or reduce the firing rate.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

1 claim:

1. A machine gun for firing cartridges provided with projectiles inclosed within cylindrical cases, said gun including a substantially cylindrical receiver, a plurality of symmetrically disposed barrels mounted in a drum disposed for rotation in said receiver to successively rotate said barrels through a firing station, a transversal raceway around the inside of said receiver, a plurality of members respectively provided with a firing chamber for receiving the cartridges for discharge of the projectiles through said barrels with the number of said members being greater than the number of said barrels, a train of said members disconnectedly engaged for selfsupported travel around said raceway between a charging station and the firing station, means for moving said train around said raceway in synchronism with the rotation of said barrels to axially align successive ones of said members with successive ones of said barrels at the firing station, and means for moving the cartridges into said members at the charging station and simultaneously pushing the fired cases therefrom.

2. The gun as described in claim 1 including a cradle portion of said raceway for supporting each of said members in axial alignment with one of said barrels when in the firing station.

3. The gun as described in claim 1 wherein said means for moving said train around said raceway in synchronism with the rotation of said barrels includes a shaft longitudinally disposed in said receiver for rotatably mounting said drum, a sprocket wheel fixedly mounted to said shaft, and tooth portions disposed on said sprocket wheel to form a tooth space longitudinally aligned with each of said barrels and to successively engage succeeding ones of said members to rotate said train and grip said members therebetween when moved thereby to the firing station.

4. The gun as described in claim 1 wherein said means for moving the cartridges into said members when passing through said charging station includes a feedwheel, a plurality of carriers disposed around the perimeter of said feedwheel to carry the cartridges into axial alignment with each of said members passing through said charging station, and cam means engageable by the cartridges carried in said carriers for transferring the cartridges therefrom into the corresponding ones of said members during travel thereof through the charging station.

5. The gun as described in claim 1 including an arcuate portion of said raceway disposed in said receiver for directing said members in a path concentric to said drum and radially spaced therefrom so that said firing chambers are clear of said drum when said members are moved through said charging station.

References Cited in the file of this patent UNITED STATES PATENTS 2,756,639 Bird July 31, 1956 FOREIGN PATENTS 20,275 Great Britain a- 1914 

